Beginning early next year, drivers in six states will begin testing a new way to pay for roads and transit: Commuters will be charged for the miles they drive rather than paying taxes on gasoline purchased.

Researchers from the University of Iowa Public Policy Center will install computers and satellite equipment in the vehicles of 2,700 volunteers — 450 each from Austin, Baltimore, Boise, San Diego, eastern Iowa and the Research Triangle region of North Carolina.

Over the next two years, the drivers will get sample monthly bills for the number of miles they've driven. They can compare what they now pay in gasoline taxes with what they would have paid in per-mile fees.

"We want to assess the public's attitudes and acceptance toward a system like this," says Jon Kuhl, principal investigator on the $16.5 million Road User Charge Study and chairman of the University of Iowa Department of Electrical and Computer Engineering.

The nation is reassessing the way it pays for roads and transit. Since 1956, the Highway Trust Fund, financed by the federal tax on gasoline, has been a primary source of money for highway projects. But the National Governors Association and other groups and planners involved in road building have concluded that this method, supplemented by state gasoline taxes, no longer is adequate.

Americans are driving cars that get better mileage, and more are driving vehicles that use fuels taxed at lower rates than gasoline, such as ethanol, or making their own fuel and not being taxed. That means gas tax revenue isn't growing nearly as fast as the number of miles driven.

In addition, the costs of road construction materials have skyrocketed because of heavy demand from India and China. Congress and many state legislatures are reluctant to increase gas taxes, especially at a time of high prices at the pump. The federal gas tax of 18.4 cents a gallon has not been increased since 1993; 24 states have not raised their gas taxes since 1997, according to the American Road & Transportation Builders Association.

That has made a mileage fee more attractive to some agencies. The University of Iowa study is funded by the Federal Highway Administration and 15 state departments of transportation.

Elsewhere:

•Oregon this year finished a year-long experiment that tested a "virtual tollway" system that could eventually replace the state gas tax with a road-user fee. Volunteers drove vehicles equipped with state-installed Global Positioning System (GPS) devices and odometers that kept track of the miles they drove. When they gassed up, the drivers paid for their gas as well as 1.2 cents for each mile driven since their last fill-up; they did not pay the 24-cents-a-gallon state gas tax.

•Minnesota Gov. Tim Pawlenty says part of his state's plan for dealing with declining gas tax revenues is a mileage tax or fee. He wants a test project this year.

•Colorado Gov. Bill Ritter appointed a 32-member commission in March to explore long-term options, including mileage fees.

Some transportation experts believe that mileage fees will replace the gas tax within the next 15-20 years. "At some point, in some metro areas, market-based pricing using the latest technology will supplant the fuel tax revenues," says Joseph Giglio, a professor at Northeastern University who has written extensively on transportation financing.

Privacy advocates worry about the use of satellite navigation technology to track drivers' movements. "Where you go is something that, for the most part, people consider private," says Lee Tien, an attorney who specializes in privacy issues for the San Francisco-based Electronic Frontier Foundation. "The second point is, it's the sort of thing we do to the bad guys. Where do you hear a lot about GPS tracking? It's for prisoners or people who are out on probation."

James Whitty, who headed the Oregon experiment, says some of the 260 volunteers initially had privacy concerns, but those worries faded. He says that 91% of those surveyed said they would pay a mileage fee if the program were expanded statewide.

Leroy Younglove, a participant in the Oregon study, says he had no privacy concerns and that the mileage fee is fairer than the gas tax. "I thought it was an interesting alternative to the method we have now and one that might have ways of obtaining tax revenues as different types of fuel options become available," says Younglove, 63, who manages real estate.

"It's not a question of if this is viable," says Iowa's Kuhl. "It's a question of when it becomes politically and socially viable to make such a large-scale shift."

To report corrections and clarifications, contact Reader Editor Brent Jones. For publication consideration in the newspaper, send comments to letters@usatoday.com. Include name, phone number, city and state for verification.

Shelley Snow drives last year with a dashboard device that tracks her mileage as part of an Oregon pilot project.

Conversation guidelines: USA TODAY welcomes your thoughts, stories and information related to this article.
Please stay on topic and be respectful of others. Keep the conversation appropriate for interested readers across the map.